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How Thermodynamic, Electronic, and Steric Factors Influence Mesitylcopper Oligomers

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Mesitylcopper (CuMes) is a highly versatile organocopper reagent used in both organic and inorganic syntheses. It has previously been shown that CuMes exists as a tetrameric or pentameric cyclic oligomer [CuMes] n ( n = 4, 5), both in solution and in the solid state. The bonding arrangement between the [CuMes] units has qualitatively been described as localized three-center two-electron (3c-2e) bonds. However, the electronic, structural, and thermodynamic forces driving this aggregation are still not well understood. For this reason, we employed density functional theory (DFT) calculations to study mesitylcopper as a monomeric [CuMes] unit and [CuMes] n oligomers with n = 2 to n = 7. We found that there is a strong electronic driving force for aggregation caused by strong mixing between the Cu’s d orbitals and Mes’s π orbitals in oligomers larger than the dimer. This mixing is only optimized in oligomers with n ≥ 3, where the mesityl group is no longer bonded to a single copper center but instead becomes a bridging ligand. Beyond the trimer, steric and entropic factors become relevant for determining the relative stabilities of the different aggregates, with midsized oligomers ( n = 4–5) having the optimal balance between the electronic Cu–C bonding character, Cu···Cu attractive forces, entropy, reduced internal ring strain, and reduced steric interactions between the mesityl groups.

Source: The Journal of Physical Chemistry A

DOI: 10.1021/acs.jpca.5c04666

Authors: D.P. Ngan Le, Michael Stollenz, Samer Gozem

Institutions: Georgia State University, Kennesaw State University

Language: English

Topic: Coordination Chemistry and Organometallics

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid